Process for purification of hydrocarbon oils



Patented Dec. 23, 1930 UNITED STATES PATE OFFICE EDWARD 18. 11mm, or BOSELLE, NEW JERSEY, assienon r STANDARD ornn v Lor- KENT couramr, A CORPORATION or DELAWAR PROCESS FOR PURIFICATION OF H YDBGGARBON OILS llo Drawing.

' The present invention relates to the art of purifying hydrocarbon oils and more speciflcally comprises an improved process for sweetening sour distillates of petroleum and the like, as will be fully understood from the following description.

Hydrocarbon oils, in particular the low boiling distillates which make ug the gasoline and kerosene of commerce, 0 en contain impurities of a sulfurous nature which it is desirable to remove or modify. The presence of certain impurities is detected by the doctor test which is well knownin the art and has been fully described in Technical Paper 323 5 of the United States Bureau of Mines, page 83. Oils which fail to pass this test are known as sour oils and it is customary to sweeten such oils by a treatment with doctor solution, which is a solution of lith'arge in aqueous go caustic soda, as is well known. In carrying out the sweetening process the oil is agitated with doctor solution. It is customary to add flowers of sulfur to precipitate the lead as lead sulfide and to allow the 1. aqueous and oily layers to separate. There is considerable ,difliculty in adding. the exact uantity of sulfur and if an excessis added, t e oil will be corrosive, which is undesirable.

My invention comprises adding a low boiling alkyl disulfide to the oil instead of flowers of sulfur and I have found that b such addition a precipitate is formed whic may be removed, and that the remaining oil is sweet to the doctor test. An excess of disulfide is not detrimental either. in respect to sourness or corrosion.

I have found that methyl, ethyl, or propyl disulfide or a mixture of two or more of these sulfides is satisfactory for my process and that such disulfides may be added to the oil before or after the doctor treatment. The re-- action is relatively slow but may be hastened by warming.

The preclpitate formed bythe addition of sponding alkyl-lead mercaptide with or without lead sulfide, depending on the particular impurities in the souroil.

My process may be carried out in any form of treating apparatus know-n in the art,

liquid products extracted from refine alkyl disulfide is found to contain the corre-[ Application and July 1,.1e27f's r a1 No. 202,979.

.either batch -or continuous. The disulfide may be added to apart of the oil, which is then agitated with the bulk of the oil, if so desired. In treating very sour oils where the quantity of disulfide required is large, I contemplate adding sulfur according to the pres ent practice, but in quantit insuflicient to completely sweetenthe oil, then to complete the process by addition of alkyl disulfide, as described,

As an example of my process, 250 cc. of sour crackednaphtha having a gravity of 49.7 9 A. P. I. anda sulfur content of 265% is agitated about fi'minutes with doctor solution. The oil is separated and .20 cc. of N-propyl disulfide added. The mixture .is agitated and after standing for several hours, a dark yellow precipitate separates and is filtered from the oil, which now passes. the doctor test and is non-corrosive,- asindicated by. the fact .that it will not tarnish a strip of bright copper submerged in the oil for onehalf hour at212-F. The sulfur content-of theoil is".288%. g i '1' i As a second example of my process, 200 cc. of sour water white .distillate, 425 A. P. I., with sulfur content of 210%, is treated with doctor solution'and after separation of the aqueous layer .20 cc. of methyl disulfide is added. The oil is heated in a steam bath and after six hours the precipitate is filtered off. The color of the oilis found to be improved, it passes the doctor test and is non-corrosive according to the test specified in the first example. The sulfur content is now 244%.

My invention has been described particularly in respect to the sweetening of gasoline and kerosene from petroleum but it is applicable to the treatment of other hydrocarbon oils, such as natural gas gasoline and as coal gas, and the like. My invention 1s not to be limited by any theory of the mechanism of the reaction nor by any example given merely by way of illustration, but only by the following claims, in which I wish to claim all novelty inherent in my invention.

I claim:

1. The process of improving light hydrocarbon distillate, comprlsing treatlng the distillate with doctor solution and then adding a low boiling alkyl disulfide to the distillate.

2. The process of improving light hydrocarbon distillate, comprlsing treatmg the distillate with doctor solution, adding a low boiling alkyl disulfide, and separating the precipitate formed thereby from the distillate.

3. The process of sweetening light hydrocarbon distillate, comprising treating the distillate with doctor solution, adding an alkyl disulfide characterized by the fact that the corresponding alkyl lead merca tide is insoluble in distillate, and filtering t e recipitated lead mercaptide from the distillate.

4. A process of sweetening light hydrocarbon distillate, comprising treatlng the distillate with doctor solution, adding thereto a mixture of organic disulfides comprising methyl, ethyl and propyl disulfides, and removm the precipitate formed thereby.

5. T e process of sweetening light hydrocarbon distillate, comprising treating the distillate with doctor solution, adding sulfur to the distillate less than sufficient to com letely precipitate the lead as lead sulfide, a ding a low boiling alkyl disulfide to the distillate and separating the precipitate so formed.

6. The process of sweetening light hydrocarbon distillate, comprising treating the distillate with doctor solution, withdrawing the aqueous spent doctor solution, adding a low boiling alkyl disulfide to the distillate and separating from the distillate the precipitate so formed.

7. The process according to claim 3, in which the reaction is carried out at a temperature above normal atmospheric temperature.

8. The process of sweetening light hydrocarbon distillate, comprising addin a low boiling alkyl disulfide to the distil ate and then treatin with doctor solution in the presence of t e alkyl disulfide.

EDWARD B. HUNN. 

